Wireless power transmitting unit, wireless power receiving unit, and control methods thereof

ABSTRACT

A control method of a wireless power receiving unit receiving charging power from a wireless power transmitting unit to perform wireless charging is provided. The control method includes receiving the charging power from the wireless power transmitting unit; detecting a change in a wireless charging environment; generating a message notifying of the change in the wireless charging environment; and transmitting the message notifying of the change in the wireless charging environment to the wireless power transmitting unit.

PRIORITY

This application is a continuation of, and claims priority under 35U.S.C. § 120 to, U.S. patent application Ser. No. 14/221,530, filed onMar. 21, 2014 and issuing on Dec. 6, 2016 as U.S. Pat. No. 9,515,514,which claimed priority under 35 U.S.C. § 119(a) to Korean Pat. App. Ser.Nos. 10-2013-0030568 and 10-2013-0155925, which were filed in the KoreanIntellectual Property Office on Mar. 21, 2013 and Dec. 13, 2013,respectively; the entire content of all of the above is incorporatedherein by reference.

BACKGROUND

1. Field of the Invention

The present invention generally relates to a wireless power transmittingunit, a wireless power receiving unit, and control methods thereof, andmore particularly, to a wireless power transmitting unit, a wirelesspower receiving unit, and control methods thereof, which can wirelesslytransmit/receive charging power.

2. Description of the Related Art

Wireless charging or non-contact charging technologies have beendeveloped to be currently used for many electronic devices. Such awireless charging technology employs wireless powertransmission/reception, and corresponds to, for example, a system inwhich a battery can be automatically charged if the battery is placed ona charging pad, without the need for connecting the electronic device toa separate charging connector. The wireless charging technology canincrease a waterproof function through wirelessly charging electronicproducts and increase portability of the electronic device because thereis no need for a wired charger.

Among the wireless charging technologies, charging using a resonancescheme is performed as follows. When a wireless power receiving unit(for example, a portable terminal) requiring charging is located on awireless power transmitting unit (for example, a charging pad)transmitting wireless power, the wireless power transmitting unit maycharge the wireless power receiving unit. When a plurality of wirelesspower receiving units are located on a charging area of one wirelesspower transmitting unit, power required by each of the wireless powerreceiving units may be different from the transmitted power, so thatefficient charging can be made for each of the wireless power receivingunits.

While research on a wireless charging method is currently progressing,standards for a wireless charging order, a search for a wireless powertransmitting unit/receiving unit, selection of a communication frequencybetween the wireless power transmitting unit/receiving unit, a wirelesspower control, selection of a matching circuit, and communication timedistribution to each wireless power receiving unit in one charging cyclehave not yet been proposed. Specifically, there is a need for atechnology which can deal with a situation where the wireless powerreceiving unit detects a charging environment change by notifying thewireless power transmitting unit of the detected environment change.

SUMMARY

The present invention has been made to address at least the aboveproblems and disadvantages, and to provide at least the advantagesdescribed below.

Accordingly, an aspect of the present invention provides a wirelesspower transmitting unit, a wireless power receiving unit, and controlmethods thereof, which wireless transmit and receive charging power.

In accordance with an aspect of the present invention, a control methodof a wireless power receiving unit receiving charging power from awireless power transmitting unit to perform wireless charging isprovided. The control method includes receiving the charging power fromthe wireless power transmitting unit; detecting a change in a wirelesscharging environment; generating a message notifying of the change inthe wireless charging environment; and transmitting the messagenotifying of the change in the wireless charging environment to thewireless power transmitting unit.

In accordance with another aspect of the present invention, a controlmethod of a wireless power transmitting unit transmitting charging powerto a wireless power receiving unit to perform wireless charging isprovided. The control method includes transmitting the charging power tothe wireless power receiving unit; receiving a message including arequest for maintaining output power for a mode transition time from thewireless power receiving unit; and maintaining the output power to thewireless power receiving unit for the mode transition time included inthe message.

In accordance with another aspect of the present invention, a wirelesspower receiving unit receiving charging power from a wireless powertransmitting unit to perform wireless charging is provided. The wirelesspower receiving unit includes a power receiver configured to receive thecharging power from the wireless power transmitting unit; and acommunication unit configured to detect a change in a wireless chargingenvironment, generate a message notifying of the change in the wirelesscharging environment, and transmit the message to the wireless powertransmitting unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram which illustrates a wireless charging system;

FIG. 2 is a block diagram which illustrates a wireless powertransmitting unit and a wireless power receiving unit according to anembodiment of the present invention;

FIG. 3 is a block diagram illustrating in detail a wireless powertransmitting unit and a wireless power receiving unit according to anembodiment of the present invention;

FIG. 4 is a flow diagram illustrating operations of a wireless powertransmitting unit and a wireless power receiving unit according to anembodiment of the present invention;

FIG. 5 is a flowchart illustrating operations of a wireless powertransmitting unit and a wireless power receiving unit according toanother embodiment of the present invention;

FIG. 6 is a graph on an x axis of an amount of power applied by awireless power transmitting unit;

FIG. 7 is a flowchart illustrating a control method of a wireless powertransmitting unit according to an embodiment of the present invention;

FIG. 8 is a graph on an x axis of an amount of power applied by awireless power transmitting unit according to the embodiment of FIG. 7;

FIG. 9 is a flowchart illustrating a control method of a wireless powertransmitting unit according to an embodiment of the present invention;

FIG. 10 is a graph on an x axis of an amount of power applied by awireless power transmitting unit according to the embodiment of FIG. 9;

FIG. 11 is a block diagram of a wireless power transmitting unit and awireless power receiving unit in an SA mode according to an embodimentof the present invention;

FIG. 12 is a block diagram of a wireless power transmitting unit and awireless power receiving unit in an NSA mode according to an embodimentof the present invention;

FIG. 13 is a flowchart illustrating operations of a wireless powertransmitting unit and a wireless power receiving unit according to anembodiment of the present invention;

FIG. 14 is a flowchart illustrating a control method of a wireless powerreceiving unit based on a mode transition according to an embodiment ofthe present invention; and

FIG. 15 is a flowchart illustrating a control method of a wireless powertransmitting unit based on a mode transition according to an embodimentof the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Hereinafter, various embodiments of the present invention will bedescribed more specifically with reference to the accompanying drawings.It should be noted that the same components of the drawings aredesignated by the same reference numeral throughout the figures. In thefollowing description of the present invention, a detailed descriptionof known functions and configurations incorporated herein will beomitted when it may make the subject matter of the present disclosureunclear.

According to at least one embodiment of the present invention, awireless power transmitting unit supplying wireless power and a wirelesspower receiving unit receiving the wireless power to perform chargingperform communication with each other for controlling wireless powertransmission by using non-contact short-range wireless communication. Ina dead battery state in which power sufficient to turn on an ApplicationProcessor (hereinafter referred to as an AP) cannot be supplied,wireless charging can be performed using only some components for thewireless charging within the wireless power receiving unit. For example,it is possible to perform wireless charging by using a non-contactshort-range wireless communication module basically embedded in awireless power receiving unit without a separate communication modulefor performing the wireless charging. Thereafter, when the AP is drivenas a battery is charged, the wireless charging can be performed byloading a stack from the AP. At this time, as the AP is driven, apredetermined time is spent until a mode transition is completed.

In an embodiment of the present invention, the wireless powertransmitting unit is informed of the mode transition and thus can standby for a time spent when the mode transition is completed. According tothe mode transition, the wireless power transmitting unit recognizes amode transition condition in the wireless power receiving unit tomaintain a connection with the wireless power receiving unit even thoughthe wireless power transmitting unit does not receive a response fromthe wireless power receiving unit for a predetermined time.

In an embodiment of the present invention, a BlueTooth (BT) scheme or aBluetooth Low Energy (BLE) scheme may be used as an example of a lowenergy wireless communication scheme of the non-contact short-rangewireless communication scheme. The low energy wireless communicationscheme consuming a minimum of power may include other short-rangewireless communication schemes such as Zigbee communication, wirelessIrDA, and the like, as well as the aforementioned schemes. Further, anon-contact short-range wireless communication unit may be configured byone chip which can support a wireless network scheme as well as the lowenergy wireless communication scheme. Accordingly, a WiFi scheme is usedas an example of the wireless network scheme.

Further, a wireless charging method according to an embodiment of thepresent invention can be applied to any device which receives wirelesspower to perform charging through electronic device wireless charging,an electric car wireless power supply, a long-distance wireless powersupply, a ubiquitous wireless sensor power supply, and the like. Inaddition, wireless charging is performed using a non-contact short-rangewireless communication module basically embedded in the wireless powerreceiving unit without a separate communication module for the wirelesscharging, so that the separate communication module for the wirelesscharging is not needed. As a result, manufacturing costs can be reduced.

FIG. 1 illustrates a wireless charging system. As shown in FIG. 1, thewireless charging system includes a wireless power transmitting unit 100and one or more wireless power receiving units 110-1, 110-2, . . . , and110-n.

The wireless power transmitting unit 100 wirelessly transmits power 1-1,1-2, . . . , and 1-n to the one or more wireless power receiving units110-1, 110-2, . . . , and 110-n, respectively. The wireless powertransmitting unit 100 may wirelessly transmit the power 1-1, 1-2, . . ., and 1-n only to the wireless power receiving units authorized througha preset authentication process.

The wireless power transmitting unit 100 forms wireless connections withthe wireless power receiving units 110-1, 110-2, . . . , and 110-n. Forexample, the wireless power transmitting unit 100 transmits wirelesspower to the wireless power receiving units 110-1, 110-2, . . . , and110-n through electromagnetic waves.

The one or more wireless power receiving units 110-1, 110-2, . . . , and110-n wirelessly receive power from the wireless power transmitting unit100 to charge batteries inside the wireless power receiving units 110-1,110-2, . . . , and 110-n. Further, the one or more wireless powerreceiving units 110-1, 110-2, . . . , and 110-n may transmit messages2-1, 2-2, . . . , and 2-n including a request of wireless powertransmission, information required for reception of wireless power,state information of the wireless power receiving units 110-1, 110-2, .. . , and 110-n and information (that is, control information) forcontrolling the wireless power transmitting unit 100 to the wirelesspower transmitting unit 100. Similarly, the wireless power transmittingunit 100 may transmit a message including state information of thewireless power transmitting unit 100 and information (that is, controlinformation) for controlling the wireless power receiving units 110-1,110-2, . . . , and 110-n to the wireless power receiving units 110-1,110-2, . . . , and 110-n.

Further, each of the wireless power receiving units 110-1, 110-2, . . ., and 110-n may transmit a message indicating a charging state to thewireless power transmitting unit 100.

The wireless power transmitting unit 100 includes a display unit such asa display, and displays a state of each of the wireless power receivingunits 110-1, 110-2, and 110-n based on the message received from each ofthe wireless power receiving units 110-1, 110-2, . . . , and 110-n.Further, the wireless power transmitting unit 100 may also display atime expected to be spent until each of the wireless power receivingunits 110-1, 110-2, . . . , and 110-n is completely charged.

The wireless power transmitting unit 100 transmits a control signal (orcontrol message) for disabling a wireless charging function of each ofthe one or more wireless power receiving units 110-1, 110-2, . . . , and110-n. The wireless power receiving units having received the disablecontrol signal of the wireless charging function from the wireless powertransmitting unit 100 disable the wireless charging function.

FIG. 2 illustrates a wireless power transmitting unit and a wirelesspower receiving unit according to an embodiment of the presentinvention.

As illustrated in FIG. 2, the wireless power transmitting unit 200includes at least a power transmitter 211, a controller 212, acommunication unit 213 and may also include, a display unit 214, and astorage unit 215. Further, the wireless power receiving unit 250includes a power receiver 251, a controller 252, and a communicationunit 253.

The power transmitter 211 supplies power which is required by thewireless power transmitting unit 200, and wirelessly provides power tothe wireless power receiving unit 250. The power transmitter 211 maysupply power in an Alternating Current (AC) waveform type, or convertpower in a Direct Current (DC) waveform type to the power in the ACwaveform type by using an inverter, and then supply the power in the ACwaveform type. The power transmitter 211 may be implemented in a form ofan embedded battery or in a form of a power receiving interface so as toreceive the power from outside thereof and supply the power to the othercomponents. It will be easily understood by those skilled in the artthat the power transmitter 211 is not limited if it supplies power ofconstant alternate current waves.

The controller 212 controls overall operations of the wireless powertransmitting unit 200. The controller 212 controls overall operations ofthe wireless power transmitting unit 200 by using an algorithm, aprogram, or an application which is required for a control and read fromthe storage unit 215. The controller 212 may be implemented in a form ofa CPU, a microprocessor, a mini computer and the like.

The communication unit 213 communicates with the wireless powerreceiving unit 250 in a specific manner. The communication unit 213receives power information from the wireless power receiving unit 250.Here, the power information includes at least one of a capacity of thewireless power receiving unit 250, a residual amount of the battery, anumber of times of charging, an amount of use, a battery capacity, and aproportion of the remaining battery capacity. Further, the communicationunit 213 transmits a signal of controlling a charging function in orderto control the charging function of the wireless power receiving unit250. The signal of controlling the charging function may be a controlsignal of controlling the power receiver 251 of the wireless powerreceiving unit 250 so as to enable or disable the charging function.More specifically, the power information may include information on aninsertion of a wireless charging terminal, a transition from a StandAlone (SA) mode to a Non-Stand Alone (NSA) mode, error state release andthe like.

The communication unit 213 may receive a signal from another wirelesspower transmitting unit (not shown) as well as from the wireless powerreceiving unit 250.

The controller 212 may display a state of the wireless power receivingunit 250 on a display unit 214 based on the message received from thewireless power receiving unit 250 through the communication unit 213.Further, the controller 212 may also display a time expected to be spentuntil the wireless power receiving unit is completely charged on thedisplay unit 214.

FIG. 3 is a block diagram illustrating in detail the wireless powertransmitting unit and the wireless power receiving unit according to anembodiment of the present invention.

As illustrated in FIG. 3, the wireless power transmitting unit 200includes the power transmitter 211, the controller/communication unit(MCU & Out-of-band Signaling) 212/213, a driver (Power Supply) 217, anamplifier (Power Amp) 218, and a matching unit (Matching Circuit) 216.The wireless power receiving unit 250 includes the power receiver 251,the controller/communication unit 252/253, a DC/DC converter 255, aswitching unit (Switch) 256, and a loading unit (Client Device Load)257.

The driver 217 may output DC power having a preset voltage value. Thevoltage value of the DC power output by the driver 217 may be controlledby the controller/communication unit 212/213.

The DC power output from the driver 217 is output to the amplifier 218,which amplifies the DC power by a preset gain. Further, the amplifier218 converts DC power to AC power based on a signal input from thecontroller/communication unit 212/213. Accordingly, the amplifier 218outputs AC power.

The matching unit 216 performs impedance matching. For example, thematching unit 216 may adjust impedance viewed from the matching unit 216to control output power to be high efficient or high output power. Thematching unit 216 may also adjust impedance based on a control of thecontroller/communication unit 212/213. The matching unit 216 includes atleast one of a coil and a capacitor. The controller/communication unit212/213 controls a connection state with at least one of the coil andthe capacitor, and accordingly, performs impedance matching.

The power transmitter 211 transmits input AC power to the power receiver251. The power transmitter 211 and the power receiver 251 may beimplemented by resonant circuits having the same resonance frequency.For example, the resonance frequency may be determined to be 6.78 MHz.

Meanwhile, the controller/communication unit 212/213 communicates withthe controller/communication unit 252/253 of the wireless powerreceiving unit 250, and perform communication (WiFi, ZigBee, or BT/BLE),for example, with a bi-directional 2.4 GHz frequency.

The power receiver 251 receives charging power.

The rectifying unit 254 rectifies wireless power received by the powerreceiver 251 in the form of direct current, and is implemented in a formof bridge diode. The DC/DC converter 255 converts the rectified electriccurrent into a predetermined gain. For example, the DC/DC converter 255converts the rectified electric current so that a voltage of an outputend 259 becomes 5V. Meanwhile, a minimum value and a maximum value ofthe voltage which can be applied may be preset for a front end 258 ofthe DC/DC converter 255.

The switching unit 256 connects the DC/DC converter 255 to the loadingunit 257. The switching unit 256 is held in an on/off state under acontrol of the controller 252. In a case where the switch 256 is in theon state, the loading unit 257 stores converted electric power which isinput from the DC/DC converter 255.

FIG. 4 is a flow diagram illustrating operations of the wireless powertransmitting unit and the wireless power receiving unit according to anembodiment of the present invention. As illustrated in FIG. 4, awireless power transmitting unit 400 applies power in step S401. Whenthe power is applied, the wireless power transmitting unit 400configures an environment in S402.

The wireless power transmitting unit 400 enters a power saving mode instep S403. In the power saving mode, the wireless power transmittingunit 400 may apply different types of power beacons for detectionaccording to their own periods, which will be described in more detailwith reference to FIG. 6. For example, in FIG. 4, the wireless powertransmitting unit 400 applies detection power beacons 404 and 405, andthe sizes of power values of the detection power beacons 404 and 405 maybe different. A part or all of the detection power beacons 404 and 405may have power enough to drive the communication unit of the wirelesspower receiving unit 450. For example, the wireless power receiving unit450 may drive the communication unit by the part or all of the detectionpower beacons 404 and 405 to communicate with the wireless powertransmitting unit 400. The above state may be named a null state in stepS406.

The wireless power transmitting unit 400 detects a load change by anarrangement of the wireless power receiving unit 450. The wireless powertransmitting unit 400 may enter a low power mode in step S409. The lowpower mode will be described in more detail with reference to FIG. 6.Meanwhile, the wireless power receiving unit 450 may drive thecommunication unit based on power received from the wireless powertransmitting unit 400 in step S409.

The wireless power receiving unit 450 transmits a Power TransmittingUnit (PTU) searching signal to the wireless power transmitting unit 400in step S410. The wireless power receiving unit 450 transmits the PTUsearching signal as an advertisement signal based on a Bluetooth LowEnergy (BLE) scheme. The wireless power receiving unit 450 may transmitthe PTU searching signal periodically or until a preset time arrives,and receives a response signal from the wireless power transmitting unit400.

When receiving the PTU searching signal from the wireless powerreceiving unit 450, the wireless power transmitting unit 400 transmits aPRU response signal in step S411. The Power Receiving Unit (PRU)response signal forms a connection between the wireless powertransmitting unit 400 and the wireless power receiving unit 450. Thewireless power receiving unit 450 transmits a PRU static signal in stepS412. The PRU static signal may be a signal indicating that the wirelesspower receiving unit 450 may make a request for joining the wirelesspower network managed by the wireless power transmitting unit 400.

The wireless power transmitting unit 400 transmits a PTU static signalin step S413. The PTU static signal transmitted by the wireless powertransmitting unit 400 may be a signal indicating a capability of thewireless power transmitting unit 400.

When the wireless power transmitting unit 400 and the wireless powerreceiving unit 450 transmit and receive the PRU static signal and thePTU static signal, the wireless power receiving unit 450 periodicallytransmits a PRU dynamic signal in steps S414 and S415. The PRU dynamicsignal includes at least one parameter information measured by thewireless power receiving unit 450. For example, the PRU dynamic signalmay include voltage information of a back end of the rectifier of thewireless power receiving unit 450. The state of the wireless powerreceiving unit 450 may be called a boot state in step S407.

The wireless power transmitting unit 400 enters a power transmissionmode in step S416 and transmits a PRU control signal corresponding to acommand signal to allow the wireless power receiving unit 450 to becharged in step S417. In the power transmission mode, the wireless powertransmitting unit 400 transmits charging power.

The PRU control signal transmitted by the wireless power transmittingunit 400 may include information enabling/disabling the charging of thewireless power receiving unit 450 and permission information. The PRUcontrol signal is transmitted whenever a charging state is changed. ThePRU control signal may be transmitted, for example, every 250 ms, ortransmitted when a parameter is changed. The PRU control signal may beset to be transmitted within a preset threshold, for example, within onesecond even though the parameter is not changed.

The wireless power receiving unit 450 may change a configurationaccording to the PRU control signal and transmits the PRU dynamic signalfor reporting the state of the wireless power receiving unit 450 insteps S418 and S419. The PRU dynamic signal transmitted by the wirelesspower receiving unit 450 may include at least one of information on avoltage, a current, a state of the wireless power receiving unit, andtemperature. The state of the wireless power receiving unit 450 iscalled an on state in step S421.

Meanwhile, the PRU dynamic signal may have a data structure as shown inTable 1 below.

TABLE 1 Field octets description use units optional 1 defines whichoptional mandatory fields fields are populated Vrect 2 DC voltage at theoutput mandatory mV of the rectifier. Irect 2 DC current at the outputmandatory mA of the rectifier. Vout 2 voltage at optional mVcharge/battery port Iout 2 current at optional mA charge/battery porttemperature 1 temperature of PRU optional Deg C. from −10 C. Vrect 2 Thecurrent dynamic optional mV min dyn minimum rectifier voltage desiredVrect 2 desired Vrect optional mV set dyn (dynamic value) Vrect 2 Thecurrent dynamic optional mV high dyn maximum rectifier voltage desiredPRU alert 1 warnings mandatory Bit field RFU 3 undefined

As shown in Table 1, the PRU dynamic signal may include one or morefields. The fields include optional field information, voltageinformation of a back end of the rectifier of the wireless powerreceiving unit (‘Vrect’), current information of the back end of therectifier of the wireless power receiving unit (‘Irect’), voltageinformation of a back end of the DC/DC converter of the wireless powerreceiving unit (‘Vout’), current information of the back end of theDC/DC converter of the wireless power receiving unit (‘Iout’),temperature information (‘temperature’), minimum voltage valueinformation of the back end of the rectifier of the wireless powerreceiving unit (‘Vrect min dyn’), optimal voltage value information ofthe back end of the rectifier of the wireless power receiving unit(‘Vrect set dyn’), maximum voltage value information of the back end ofthe rectifier of the wireless power receiving unit (‘Vrect high dyn’),alert information (‘PRU alert’) and RFU (Reserved for Future Use). ThePRU dynamic signal may include at least one of the above fields.

For example, one or more voltage setting values (for example, theminimum voltage value information (Vrect min dyn) of the back end of therectifier of the wireless power receiving unit, the optimal voltagevalue information (Vrect set dyn) of the back end of the rectifier ofthe wireless power receiving unit, and the maximum voltage valueinformation (Vrect high dyn) of the back end of the rectifier of thewireless power receiving unit) determined according to a charging statemay be inserted into corresponding fields and then transmitted. Asdescribed above, the wireless power receiving unit having received thePRU dynamic signal controls a wireless charging voltage to betransmitted to each of the wireless power receiving units with referenceto the voltage setting values included in the PRU dynamic signal.

Among them, the alert information (PRU Alert) may have a data structureshown in Table 2 below,

TABLE 2 7 6 5 4 3 2 1 0 over- over- over- Charge TA Tran- restart RFUvoltage current temper- Complete detect sition request ature

Referring to Table 2, the alert information (PRU Alert) may include abit for a restart request, a bit for a transition, and a bit fordetecting an insertion of a Travel Adapter (TA) (TA detect). The TAdetect indicates a bit informing of a connection between the wirelesspower transmitting unit providing wireless charging and a terminal forwired charging by the wireless power receiving unit. The transitionindicates a bit informing the wireless power transmitting unit that thewireless power receiving unit is reset before a communication IntegratedCircuit (IC) of the wireless power receiving unit is switched from aStand Alone (SA) mode to a Non Stand Alone (NSA) mode. Lastly, therestart request indicates a bit informing the wireless power receivingunit that the wireless power transmitting unit is ready to restart thecharging when the charging is disconnected since the wireless powertransmitting unit reduces power due to the generation of an over currentstate or a over temperature state and then the state is returned to anoriginal state.

Further, the alert information (PRU Alert) may also have a datastructure shown in Table 3 below.

TABLE 3 7 6 5 4 3 2 1 0 PRU PRU PRU PRU Charge Wired Mode Mode over-over- over- Self Com- Charger Tran- Tran- voltage current temper- Pro-plete Detect sition sition ature tection Bit 1 Bit 0

Referring to Table 3 above, the alert information may include overvoltage, over current, over temperature, PRU self protection, chargecompete, wired charger detect, mode transition and the like. When theover voltage field is set as “1”, it may indicate that a voltage Vrectof the wireless power receiving unit exceeds a limit of the overvoltage. Further, the over current and the over temperature may be setin the same way as the over voltage. The PRU self protection indicatesthat the wireless power receiving unit directly reduces a load of powerand thus protects itself. In this event, the wireless power transmittingunit is not required to change a charging state.

Bits for a mode transition according to an embodiment of the presentinvention may be set as a value informing the wireless powertransmitting unit of a period during which a mode transition process isperformed. The bits indicating the mode transition period may beexpressed as shown in Table 4 below.

TABLE 4 Value (Bit) Mode Transition Bit Description 00 No ModeTransition 01 2 s Mode Transition time limit 10 3 s Mode Transition timelimit 11 6 s Mode Transition time limit

Referring to Table 4 above, “00” indicates that there is no modetransition, “01” indicates that a time required for completing the modetransition is a maximum of two seconds, “10” indicates that a timerequired for completing the mode transition is a maximum of threeseconds, and “11” indicates that a time required for completing the modetransition is a maximum of six seconds.

For example, when three seconds or less are spent for completing themode transition, the mode transition bit may be set as “10”. Prior tostarting the mode transition process, the wireless power receiving unitmay make a restriction such that there is no change in impedance duringthe mode transition process by changing an input impedance setting tomatch 1.1 W power draw. Accordingly, the wireless power transmittingunit may control power (ITX_COIL) for the wireless power receiving unitin accordance with the setting, and accordingly, maintain the power(ITX_COIL) for the wireless power receiving unit during the modetransition period. Accordingly, when the mode transition period is setby the mode transition bit, the wireless power transmitting unitmaintains the power (ITX_COIL) for the wireless power receiving unitduring the mode transition time, for example, three seconds. That is,the wireless power transmitting unit may maintain a connection eventhough a response is not received from the wireless power receiving unitfor three seconds. However, after the mode transition time passes, thewireless power receiving unit may be considered as a rogue object(foreign substance) and thus power transmission may be terminated.

Meanwhile, the wireless power receiving unit 450 may detect generationof errors. The wireless power receiving unit 450 transmits an alertsignal to the wireless power transmitting unit 400 in step S420. Thealert signal may be transmitted as the PRU dynamic signal or the alertsignal. For example, the wireless power receiving unit 450 may transmitthe PRU alert field of Table 3 reflecting an error state to the wirelesspower transmitting unit 400. Alternatively, the wireless power receivingunit 450 may transmit a single alert signal indicating the error stateto the wireless power transmitting unit 400. When receiving the alertsignal, the wireless power transmitting unit 400 enters a latch faultmode in step S422, and the wireless power receiving unit 450 may enter anull state in step S423.

FIG. 5 is a flowchart illustrating operations of the wireless powertransmitting unit and the wireless power receiving unit according toanother embodiment of the present invention. A control method of FIG. 5will be described in more detail with reference to FIG. 6. FIG. 6 is agraph on an x axis of a power amount applied by the wireless powertransmitting unit according to the embodiment of FIG. 5.

As illustrated in FIG. 5, the wireless power transmitting unit initiatesthe operation in step S501. Further, the wireless power transmittingunit resets an initial configuration in step S503. The wireless powertransmitting unit enters a power saving mode in step S505. The powersaving mode may correspond to an interval where the wireless powertransmitting unit applies power having different amounts to the powertransmitter. For example, the power saving mode may correspond to aninterval where the wireless power transmitting unit applies second power601 and 602 and third power 611, 612, 613, 614, and 615 to the powertransmitter in FIG. 6. The wireless power transmitting unit periodicallyapplies the second power 601 and 602 according to a second period. Whenthe wireless power transmitting unit applies the second power 601 and602, the application continues for a second term. The wireless powertransmitting unit periodically applies the third power 611, 612, 613,614, and 615 according to a third period. When the wireless powertransmitting unit applies the third power 611, 612, 613, 614, and 615,the application continues for a third term. Meanwhile, although it isillustrated that power values of the third power 611, 612, 613, 614, and615 are different from each other, the power values of the third power611, 612, 613, 614, and 615 may be different or the same.

The wireless power transmitting unit may output the third power 611 andthen output the third power 612 having the same size of the poweramount. As described above, when the wireless power transmitting unitoutputs the third power having the same size, the power amount of thethird power may have a power amount by which a smallest wireless powerreceiving unit, for example, a wireless power receiving unit designatedas Category 1 can be detected.

The wireless power transmitting unit may output the third power 611 andthen output the third power 612 having a different size of the poweramount. As described above, when the wireless power transmitting unitoutputs the third power having the different size, the power amount ofthe third power may be a power amount by which a wireless powerreceiving unit designated as Category 1 to Category 5 can be detected.For example, when the third power 611 may have a power amount by which awireless power receiving unit of Category 5 can be detected, the thirdpower 612 may have a power amount by which a wireless power receivingunit designated as Category 3 can be detected, and the third power 613may have a power amount by which a wireless power receiving unitdesignated as Category 1 can be detected.

Meanwhile, the second power 601 and 602 may be power which can drive thewireless power receiving unit. More specifically, the second power 601and 602 may have a power amount which can drive the controller and thecommunication unit of the wireless power receiving unit.

The wireless power transmitting unit applies the second power 601 and602 and the third power 611, 612, 613, 614, and 615 to the powerreceiver according to a second period and a third period, respectively.When the wireless power receiving unit is arranged on the wireless powertransmitting unit, impedance viewed from a point of the wireless powertransmitting unit may be changed. The wireless power transmitting unitdetects a change in the impedance while the second power 601 and 602 andthe third power 611, 612, 613, 614, and 615 are applied. For example,the wireless power transmitting unit may detect the change in theimpedance while the third power 615 is applied. Accordingly, referringback to FIG. 5, the wireless power transmitting unit detects an objectin step S507. When the object is not detected in step S507, the wirelesspower transmitting unit maintains a power saving mode in which differentpower is periodically applied.

Meanwhile, when there is the change in the impedance and thus the objectis detected in step S507, the wireless power transmitting unit enters alow power mode in step S509. The low power mode is a mode in which thewireless power transmitting unit applies driving power having a poweramount by which the controller and the communication unit of thewireless power receiving unit can be driven. For example, in FIG. 6, thewireless power transmitting unit applies driving power 620 to the powertransmitter. The wireless power receiving unit receives the drivingpower 620 to drive the controller and the communication unit. Thewireless power receiving unit performs communication with the wirelesspower transmitting unit according to a predetermined scheme based on thedriving power 620. For example, the wireless power receiving unit maytransmit/receive data required for an authentication and join thewireless power network managed by the wireless power transmitting unitbased on the data. However, when a rogue object is arranged instead ofthe wireless power receiving unit, data transmission/reception cannot beperformed. Accordingly, the wireless power transmitting unit determineswhether the arranged object is a rogue object in step S511. For example,when the wireless power transmitting unit does not receive a responsefrom the object within a preset time, the wireless power transmittingunit may determine the object as a rogue object.

When the object is determined as a rogue object in step S511, thewireless power transmitting unit enters a latch fault mode. When theobject is not determined as a rogue object in step S511, the wirelesspower transmitting unit performs a joining step in step S519. Forexample, the wireless power transmitting unit may periodically applyfirst power 631 to 634 according to a first period in FIG. 6. Thewireless power transmitting unit may detect a change in impedance whileapplying the first power. For example, when the rogue object iswithdrawn, the impedance change may be detected and the wireless powertransmitting unit determines that the rogue object is withdrawn.Alternatively, when the rogue object is not withdrawn, the wirelesspower transmitting unit does not detect the impedance change anddetermines that the rogue object is not withdrawn. When the rogue objectis not withdrawn, the wireless power transmitting unit may output atleast one of a lamp and a warning sound to inform a user that a state ofthe wireless power transmitting unit is an error state. Accordingly, thewireless power transmitting unit includes an output unit that outputs atleast one of a lamp and a warning sound.

When it is determined that the rogue object is not withdrawn in stepS515, the wireless power transmitting unit maintains the latch faultmode in step S513. When it is determined that the rogue object iswithdrawn in step S515, the wireless power transmitting unit enters thepower saving mode again in step S517. For example, the wireless powertransmitting unit may apply second power 651 and 652 and third power 661to 665, as shown in FIG. 6.

As described above, when the rogue object is arranged instead of thewireless power receiving unit, the wireless power transmitting unitenters the latch fault mode. Further, the wireless power transmittingunit determines whether to withdraw the rogue object by the impedancechange based on the power applied in the latch fault mode. That is, acondition of the entrance into the latch fault mode in the embodiment ofFIGS. 5 and 6 may be the arrangement of the rogue object. Meanwhile, thewireless power transmitting unit may have various latch fault modeentrance conditions as well as the arrangement of the rogue object. Forexample, the wireless power transmitting unit may be cross-connectedwith the arranged wireless power receiving unit and may enter the latchfault mode in the above case.

Accordingly, when cross-connection is generated, the wireless powertransmitting unit is required to return to an initial state and thewireless power receiving unit is required to be withdrawn. The wirelesspower transmitting unit may set the cross-connection by which thewireless power receiving unit arranged on another wireless powertransmitting unit joins the wireless power network as the latch faultmode entrance condition. An operation of the wireless power transmittingunit when the error is generated which includes the cross-connectionwill be described with reference to FIG. 7.

FIG. 7 is a flowchart illustrating a control method of the wirelesspower transmitting unit according to an embodiment of the presentinvention. The control method of FIG. 7 will be described in more detailwith reference to FIG. 8. FIG. 8 is a graph on an x axis of a poweramount applied by the wireless power transmitting unit according to theembodiment of FIG. 7.

The wireless power transmitting unit initiates the operation in stepS701. Further, the wireless power transmitting unit resets an initialconfiguration in step S703. The wireless power transmitting unit entersthe power saving mode in step S705. The power saving mode is an intervalwhere the wireless power transmitting unit applies power havingdifferent amounts to the power transmitter. For example, the powersaving mode may correspond to an interval where the wireless powertransmitting unit applies second power 801 and 802 and third power 811,812, 813, 814, and 815 to the power transmitter in FIG. 8. The wirelesspower transmitting unit periodically applies the second power 801 and802 according to a second period. When the wireless power transmittingunit applies the second power 801 and 802, the application continues fora second term. The wireless power transmitting unit periodically appliesthe third power 811, 812, 813, 814, and 815 according to a third period.When the wireless power transmitting unit applies the third power 811,812, 813, 814, and 815, the application continues for a third term.Meanwhile, although it is illustrated that power values of the thirdpower 811, 812, 813, 814, and 815 are different from each other, thepower values of the third power 811, 812, 813, 814, and 815 may bedifferent or the same.

Meanwhile, the second power 801 and 802 may be power which can drive thewireless power receiving unit. More specifically, the second power 601and 602 may have a power amount which can drive the controller and thecommunication unit of the wireless power receiving unit.

The wireless power transmitting unit applies the second power 801 and802 and the third power 811, 812, 813, 814, and 815 to the powerreceiver according to a second period and a third period, respectively.When the wireless power receiving unit is arranged on the wireless powertransmitting unit, impedance viewed from a point of the wireless powertransmitting unit may be changed. The wireless power transmitting unitdetects the impedance change while the second power 801 and 802 and thethird power 811, 812, 813, 814, and 815 are applied. For example, thewireless power transmitting unit may detect the impedance change whilethe third power 815 is applied. Accordingly, referring back to FIG. 7,the wireless power transmitting unit detects an object in step S707.When the object is not detected in step S707, the wireless powertransmitting unit maintains the power saving mode in which differentpower is periodically applied in step S705.

Meanwhile, when the impedance is changed and thus the object is detectedin step S707, the wireless power transmitting unit enters the low powermode in step S709. The low power mode is a mode in which the wirelesspower transmitting unit applies driving power having a power amount bywhich the controller and the communication unit of the wireless powerreceiving unit can be driven. For example, in FIG. 8, the wireless powertransmitting unit applies driving power 820 to the power transmitter.The wireless power receiving unit receives the driving power 820 todrive the controller and the communication unit. The wireless powerreceiving unit performs communication with the wireless powertransmitting unit according to a predetermined scheme based on thedriving power 820. For example, the wireless power receiving unit maytransmit/receive data required for an authentication and join thewireless power network managed by the wireless power transmitting unitbased on the data.

Thereafter, the wireless power transmitting unit enters the powertransmission mode in which charging power is transmitted in step S711.For example, the wireless power transmitting unit applies charging power821 and the charging power may be transmitted to the wireless powerreceiving unit as illustrated in FIG. 8.

The wireless power transmitting unit determines whether an error isgenerated in the power transmission mode. The error may be thearrangement of a rogue object on the wireless power transmitting unit,the cross-connection, over voltage, over current, over temperature andthe like. The wireless power transmitting unit may include a sensingunit that may measure the over voltage, the over current, overtemperature and the like. For example, the wireless power transmittingunit may measure a voltage or a current at a reference position. Whenthe measured voltage or current is larger than a threshold, it isdetermined that conditions of the over voltage or the over current aresatisfied. Alternatively, the wireless power transmitting unit mayinclude a temperature sensing means which measures temperature at areference position of the wireless power transmitting unit. Whentemperature at the reference position is larger than a threshold, thewireless power transmitting unit determines that a condition of the overtemperature is satisfied.

Meanwhile, when an over voltage, over current, or over temperature stateis determined according to a measurement value of the temperature,voltage, or current, the wireless power transmitting unit prevents theover voltage, over current, or over temperature by reducing the wirelesscharging power by a preset value. At this time, when a voltage value ofthe reduced wireless charging power is less than a preset minimum value(for example, the minimum voltage value (VRECT MIN DYN) of the back endof the rectifier of the wireless power receiving unit), the wirelesscharging is interrupted or stopped, so that the voltage setting valuemay be re-controlled according to an embodiment of the presentinvention.

Although it has been illustrated that the error is generated since therogue object is additionally arranged on the wireless power transmittingunit in the embodiment of FIG. 8, the type of error is not limitedthereto and it will be easily understood by those skilled in the artthat the wireless power transmitting unit operates through a similarprocess with respect to the arrangement of the rogue object, thecross-connection, the over voltage, the over current, and the overtemperature.

When the error is not generated in step S713, the wireless powertransmitting unit maintains the power transmission mode in step S711.Meanwhile, when the error is generated in step S713, the wireless powertransmitting unit enters the latch fault mode in step S715. For example,the wireless power transmitting unit applies first power 831 to 835 asillustrated in FIG. 8. Further, the wireless power transmitting unit mayoutput an error generation display including at least one of a lamp anda warning sound during the latch fault mode. When it is determined thatthe rogue object is not withdrawn in step S717, the wireless powertransmitting unit maintains the latch fault mode in step S715.Meanwhile, when it is determined that the rogue object is withdrawn instep S717, the wireless power transmitting unit enters the power savingmode again in step S719. For example, the wireless power transmittingunit applies second power 851 and 852 and third power 861 to 865 of FIG.8.

In the above description, the operation in a case where the error isgenerated while the wireless power transmitting unit transmits thecharging power has been discussed. Hereinafter, an operation in a casewhere a plurality of wireless power receiving units on the wirelesspower transmitting unit receive charging power will be described.

FIG. 9 is a flowchart for describing a control method of a wirelesspower transmitting unit according to an embodiment of the presentinvention. The control method of FIG. 9 will be described in more detailwith reference to FIG. 10. FIG. 10 is a graph on an x axis of an amountof power applied by a wireless power transmitting unit according to theembodiment of FIG. 9.

As illustrated in FIG. 9, the wireless power transmitting unit transmitscharging power to a first wireless power receiving unit in step S901.Further, the wireless power transmitting unit may allow a secondwireless power receiving unit to additionally join the wireless powernetwork in step S903. The wireless power transmitting unit transmitscharging power to the second wireless power receiving unit in step S905.More specifically, the wireless power transmitting unit applies a sum ofthe charging power required by the first wireless power receiving unitand the second wireless power receiving unit to the power receiver.

FIG. 10 illustrates an embodiment of steps S901 to S905. For example,the wireless power transmitting unit maintains the power saving mode inwhich second power 1001 and 1002 and third power 1011 to 1015 areapplied. Thereafter, the wireless power transmitting unit detects thefirst wireless power receiving unit and enters the low power mode inwhich a detection power 1020 applied to the first wireless powerreceiving unit to detect is maintained. Next, the wireless powertransmitting unit enters the power transmission mode in which firstcharging power 1030 is applied. The wireless power transmitting unitdetects the second wireless power receiving unit and allows the secondwireless power receiving unit to join the wireless power network.Further, the wireless power transmitting unit applies second chargingpower 1040 having a power amount corresponding to a sum of power amountsrequired by the first wireless power receiving unit and the secondwireless power receiving unit.

Referring back to FIG. 9, the wireless power transmitting unit detectserror generation in step S907 while charging power is transmitted toboth the first and second wireless power receiving units in step S905.As described above, the error may be the arrangement of the rogueobject, the cross-connection, the over voltage, the over current, theover temperature and the like. When the error is not generated in stepS907, the wireless power transmitting unit maintains the application ofthe second charging power 1040.

Meanwhile, when the error is generated in step, the wireless powertransmitting unit enters the latch fault mode in step S909. For example,the wireless power transmitting unit applies first power 1051 to 1055according to a first period in FIG. 10. The wireless power transmittingunit determines whether both the first wireless power receiving unit andthe second wireless power receiving unit are withdrawn in step S911. Forexample, the wireless power transmitting unit may detect an impedancechange while applying the first power 1051 to 1055. The wireless powertransmitting unit determines whether both the first wireless powerreceiving unit and the second wireless power receiving unit arewithdrawn based on whether the impedance is returned to an initialvalue.

When it is determined that both the first wireless power receiving unitand the second wireless power receiving unit are withdrawn in step S911,the wireless power receiving unit enters the power saving mode in stepS913. For example, the wireless power transmitting unit applies secondpower 1061 and 1062 and third power 1071 to 1075 according to a secondperiod and a third period, respectively.

As described above, even when the wireless power transmitting unitapplies charging power to at least one wireless power receiving unit,the wireless power transmitting unit may determine whether the wirelesspower receiving unit or the rogue object is easily withdrawn when theerror is generated.

FIG. 11 is a block diagram of a wireless power transmitting unit and awireless power receiving unit in a Stand Alone (SA) mode according to anembodiment of the present invention.

A wireless power transmitting unit 1100 includes a communication unit1110, a Power Amplifier (PA) 1120, and a resonator 1130. A wirelesspower receiving unit 1150 includes a communication unit (WPTCommunication IC) 1151, an Application Processor (AP) 1152, a PowerManagement Integrated Circuit (PMIC) 1153, a Wireless Power IntegratedCircuit (WPIC) 1154, a resonator 1155, an InterFace Power Management(IFPM) IC 1157, a Travel Adapter (TA) 1158, and a battery 1159.

The communication unit 1110 may be implemented by WiFi/BlueTooth (BT)Combo IC and communicates with the communication unit 1151 in apredetermined scheme, for example, a BLE scheme. For example, thecommunication unit 1151 of the wireless power receiving unit 1150transmits a PRU dynamic signal having the data structure as shown inTable 3 to the communication unit 1110 of the wireless powertransmitting unit 1100. As described above, the PRU dynamic signalincludes at least one of voltage information, current information,temperature information, and alert information of the wireless powerreceiving unit 1150.

Based on the received PRU dynamic signal, a power value output from thepower amplifier 1120 is adjusted. For example, when the over voltage,the over current, and the over temperature are applied to the wirelesspower receiving unit 1150, a power value output from the power amplifier1120 is reduced. Further, when a voltage or current of the wirelesspower receiving unit 1150 is less than a preset value, a power valueoutput from the power amplifier 1120 is increased.

Charging power from the resonator 1130 is wirelessly transmitted to theresonator 1155.

The WPIC 1154 rectifies the charging power received from the resonator1155 and performs DC/DC conversion. The WPIC 1154 drives thecommunication unit 1151 or charges the battery 1159 by using theconverted power.

Meanwhile, a wired charging terminal may be inserted into the traveladapter 1158. A wired charging terminal such as 30-pin connector or aUniversal Serial Bus (USB) connector may be inserted into the traveladapter 1158, and the travel adapter 1158 receives power supplied froman external power source to charge the battery 1159.

The IFPM 1157 processes power applied from the wired charging terminaland outputs the processed power to the battery 1159 and the PMIC 1153.

The PMIC 1153 manages wirelessly received power, power received througha wire, and power applied to each of the components of the wirelesspower receiving unit 1150. The AP 1152 receives power information fromthe PMIC 1153 and controls the communication unit 1151 to transmit thePRU dynamic signal for reporting the power information.

Meanwhile, the travel adapter 1158 may be connected to a node 1156connected to the WPIC 1154. When the wired charging connector isinserted into the travel adapter 1158, a preset voltage, for example, 5V may be applied to the node 1156. The WPIC 1154 monitors the voltageapplied to the node 1156 to determine whether the travel adapter isinserted.

Meanwhile, the AP 1152 has a stack in a predetermined communicationscheme, for example, a WiFi/BT/BLE stack. Accordingly, in communicationfor the wireless charging, the communication unit 1151 loads the stackfrom the AP 1152 and then communicates with the communication unit 1110of the wireless power transmitting unit 1100 by using a BT or BLEcommunication scheme based on the stack.

However, a state may occur in which data for performing wireless powertransmission cannot be fetched from the AP 1152 since the AP 1152 isturned off or in which power is lost so that the AP 1152 cannot remainin an on state while the data is fetched from a memory within the AP1152.

When a residual capacity of the battery 1159 is less than a minimumpower threshold, the AP 1152 is turned off, and the wireless chargingcan be performed using some components for the wireless charging withinthe wireless power receiving unit, for example, the communication unit1151, the WPIC 1154, and the resonator 1155. A state where the AP 1152cannot be turned on may be referred to as a dead battery state.

Since the AP 1152 is not driven in the dead battery state, thecommunication unit 1151 cannot receive a stack in a predeterminedcommunication scheme, for example, a WiFi/BT/BLE stack from the AP 1152.For such a case, some of the stacks in the predetermined communicationscheme, for example, the BLE stack, are fetched within the memory 1162of the communication unit 1151 from the AP 1152 and stored in the memory1162. Accordingly, the communication unit 1151 communicates with thewireless power transmitting unit 1100 for the wireless charging by usingthe stack in the communication scheme stored in the memory 1162, thatis, a wireless charging protocol. At this time, the communication unit1151 may include a memory therewithin, and the BLE stack may be storedin a memory in a form of a ROM in the SA mode.

As described above, a mode in which the communication unit 1151 performsthe communication by using the stack of the communication scheme storedin the memory 1162 is referred to as the SA mode. Accordingly, thecommunication unit 1151 manages a charging process based on the BLEstack.

A concept of the wireless charging system which can be applied to theembodiment of the present invention has been described with reference toFIGS. 1 to 11. Hereinafter, a charging control process according to amode transition according to an embodiment of the present invention willbe described in detail with reference to FIGS. 12 to 15.

FIG. 12 is a block diagram of the wireless power transmitting unit andthe wireless power receiving unit in a Non Stand Alone (NSA) modeaccording to an embodiment of the present invention. Since each ofcomponents in FIG. 12 is the same as each of the components in FIG. 11,a detailed description thereof will be omitted. However, FIG. 12illustrates a case where the residual capacity of the battery 1159 isgreater than the preset threshold and thus the components such as the AP1152, the PMIC 1153, the IFPM 1157, and the TA 158 are activated.

When the residual capacity of the battery 1159 is greater than or equalto a minimum power threshold in a state where the AP 1152 is turned off,the AP 1152 awakens to be driven. When the AP 1152 is driven, thecommunication unit 1151 receives a stack of a predeterminedcommunication scheme, for example, a WiFi/BT/BLE stack from the AP 1152,and loads it to the memory 162. At this time, the communication unit1151 may load a communication stack in a form of a ROM fetched from theAP 1152 in the NSA mode and stores the communication stack. As describedabove, a mode in which the communication unit 1151 receives a stack of apredetermined communication scheme for the wireless charging from the AP1152 and loads the stack to the memory 1162 is referred to as the NonStand Alone (NSA) mode.

At this time, as the AP 1152 is driven, a predetermined time is spentuntil the mode transition is completed.

A mode transition time corresponds to a time required when the wirelesspower receiving unit 1150 is switched from the SA mode to the NSA modeand may be generally “three seconds”. Since the wireless power receivingunit 1150 does not receive a communication response from the wirelesspower transmitting unit 1100 during the mode transition time,registration time out may occur for one second. Therefore, in theembodiment of the present invention, the wireless power receiving unit1150 makes a request for maintaining power during the mode transitiontime by notifying the wireless power transmitting unit 1100 of thegeneration of the mode transition from the SA mode to the NSA modethrough the mode transition bit as shown in Table 3.

Operations in the wireless power transmitting unit and the wirelesspower receiving unit having the above configuration will be describedwith reference to FIG. 13.

FIG. 13 is a flowchart illustrating operations of the wireless powertransmitting unit and the wireless power receiving unit according to anembodiment of the present invention.

The wireless power transmitting unit 1100 transmits a charginginitiation command signal to the wireless power receiving unit 1150 instep S1301. In response to the signal, the wireless power receiving unit1150 performs the wireless charging by controlling a load switch to bein an on state in step S1302. The wireless power receiving unit 1150transmits the PRU dynamic signal in step S1303 and the wireless powertransmitting unit 1100 receives and analyzes the PRU dynamic signal instep S1304. Accordingly, the wireless power transmitting unit 1100 mayidentify information such as the voltage, current, temperature of thewireless power receiving unit 1150 or wireless charging environmentchange such as the wired charging terminal insertion.

Meanwhile, the user may insert the wired charging terminal into thewireless power receiving unit 1150 and the wireless power receiving unit1150 detects the insertion in step S1305. The wireless power receivingunit 1150 determines whether wired or wireless power is provided in stepS1306. When neither the wired nor wireless power is provided in stepS1306, the wireless power transmitting unit 1100 enters the low powermode. When it is determined that both the wired charging and thewireless charging are performed in step S1306, the IFPM 1157 of thewireless power receiving unit 1150 stops the wireless charging byreleasing the connection with the resonator 1155 in step S1308.

The wireless power receiving unit 1150 outputs wired charging terminalinsertion detection (=TA (Travel Adapter) detection) to thecommunication unit 1151 in step S1309 and the communication unit 1151transmits a wired charging terminal insertion detection (=TA (TravelAdapter) detection) signal to the wireless power transmitting unit 1100in step S1310. The wireless power transmitting unit 1100 controls thecharging power in accordance with the wired charging terminal insertiondetection signal in step S1311. For example, the wireless powertransmitting unit 1100 may make a control such that the wirelesscharging is stopped by adjusting the charging power to 0.

The wireless power transmitting unit 1100 instructs non-reception ofpower in step S1312 and transmits a load switch off signal to thewireless power receiving unit 1150 in step S1313. The wireless powerreceiving unit 1150 receives the load switch off signal to control aload switch to be in an off state in step S1314.

The wireless power receiving unit 1150 periodically transmits the PRUdynamic signal in step S1315. The wireless power transmitting unit 1100receives and analyzes the PRU dynamic signal in step S1316.

Meanwhile, the wireless power receiving unit 1150 detects that the wiredcharging terminal insertion has been released in step S1317. Forexample, the wireless power receiving unit 1150 may detect the releaseof the wired charging terminal insertion by detecting a changing in avoltage applied to a back end of the travel adapter 1158. The wirelesspower receiving unit 1150 transmits a wired charging terminal insertionrelease detection signal to the wireless power transmitting unit 1100 instep S1318. For example, the wireless power receiving unit 1150 maytransmit the wired charging terminal insertion release detection signalas the PRU dynamic signal or a single signal. The wireless powertransmitting unit 1100 detects the release of the wired chargingterminal insertion from the wireless power receiving unit 1150 byanalyzing the PRU dynamic signal or the single signal in step S1319.

The wireless power transmitting unit 1100 transmits a load switch onsignal to the wireless power receiving unit 1150 in step S1320 and thewireless power receiving unit 1150 receives the load switch on signal tocontrol the load switch to be in the on state in step S1321. Meanwhile,the wireless power transmitting unit 1100 performs the wireless chargingby controlling the charging power again and the wireless power receivingunit 1150 performs the wireless charging by controlling the load switchto be in the on state.

According to the above description, the wireless power transmitting unit1100 detects the insertion or withdrawal of the wired charging terminalinto/from the wireless power receiving unit 1150. The wireless powertransmitting unit may prevent power waste and over power from beingapplied to the wireless power receiving unit 1150 by controlling thecharging power according to the insertion or the withdrawal of the wiredcharging terminal.

Meanwhile, when the battery 1159 is discharged while the wireless powerreceiving unit 1150 performs the above described operation, the AP 1152cannot be driven. At this time, the wireless power receiving unit 1150may be arranged on the wireless power transmitting unit 1100 in a statewhere the battery 1159 is discharged.

In this event, the wireless power receiving unit 1150 drives thecommunication unit 1151 of the wireless power receiving unit 1150 byreceiving a power detection beacon. However, since the AP 1152 is notdriven as described above, the communication unit 1151 cannot fetch astack of a predetermined communication scheme, for example, a wirelesscharging protocol from the AP 1152. Accordingly, the communication unit1151 operates in the SA mode in which the communication is performedusing the stack of the communication scheme stored in the memory withinthe communication unit 1151.

Hereinafter, a control process according to the mode transition in thewireless power receiving unit will be described with reference to FIG.14.

Referring to FIG. 14, the wireless power receiving unit 1150 monitorsthe battery 1159 in step S1500 and determines whether a battery value isless than a preset threshold in step S1505. When the battery value isless than the preset threshold, the wireless power receiving unit 1150may be turned off due to discharging of the battery 1159. In theembodiment of the present invention, it is assumed that the wirelesspower receiving unit 1150 is arranged on the wireless power transmittingunit 1100 in a state where the battery 1159 is discharged. Accordingly,the wireless power receiving unit 1150 receives first power which candrive the communication unit 1151 from the wireless power transmittingunit 1100 and drives the communication 1151 by using the first power.Therefore, when the battery 1159 is discharged and the battery value isless than the preset threshold, the wireless power receiving unit 1150enters the SA mode in step S1510.

When entering the SA mode, the wireless power receiving unit 1150 mayload, for example, a BLE stack from the memory 1162 within thecommunication unit 1151 in step S1515. The communication unit 1151 ofthe wireless power receiving unit 1150 communicates with the wirelesspower transmitting unit 1100 by using the loaded BLE stack in stepS1520.

As described above, the wireless power receiving unit 1150 performs thewireless charging while operating in the SA mode. Based on theperformance of the wireless charging, the battery 1159 starts to becharged. Accordingly, it is determined whether the battery value isgreater than or equal to the preset threshold in step S1525. When thebattery value is greater than or equal to the preset threshold, thewireless power receiving unit 1150 turns on the battery 1159 and the AP1152. Accordingly, the wireless power receiving unit 1150 switches theSA mode to the NSA mode in step S1530. However, when the battery valueis less than the preset threshold, the charged power is not enough toturn on the AP 1152, so the wireless power receiving unit 1150 returnsto step S1520 and communicates with the wireless power transmitting unit1100 for the wireless charging in the SA mode.

At this time, the wireless power transmitting unit 1100 is in a powertransfer state, and the communication unit 1151 does not need to bere-initialized during a charging session when the wireless powerreceiving unit 1150 is turned on. That is, in a process of resetting thecommunication unit 1151, it is required to end a BLE link between thewireless power receiving unit 1150 and the wireless power transmittingunit 1100 and re-initiate the BLE link. Accordingly, when the wirelesspower receiving unit 1150 is turned on and thus the re-initiation of theBLE link between the wireless power receiving unit 1150 and wirelesspower transmitting unit 1100 is needed, the wireless power receivingunit 1150 informs the wireless power transmitting unit 1100 of such acondition by generating a mode transition notification message.

The mode transition notification message may use the alert information(PRU Alert) as shown in Table 3 above. Accordingly, the mode transitionnotification message is a message making a request for maintaining powerfor the mode transition time and may include a time required when themode transition is completed as shown in Table 4, that is, a requiredtime according to the mode transition. The mode transition notificationmessage may be generated and transmitted by the communication unit 1151or the AP 1152.

Accordingly, the wireless power receiving unit 1150 transmits the modetransition notification message to the wireless power transmitting unit1100 in step S1535. Subsequently, the wireless power receiving unit 1150loads the WiFi/BT/BLE stack from the AP 1152 and reinitiates thecommunication with the wireless power transmitting unit 1100 based onthe stack in step S1540.

Meanwhile, FIG. 15 is a flowchart illustrating a control method of thewireless power transmitting unit based on the mode transition accordingto an embodiment of the present invention.

Referring to FIG. 15, the wireless power transmitting unit 1100transmits charging power to the wireless power receiving unit 1150 instep S1600. The wireless power transmitting unit 1100 receives a modetransition notification message notifying of switching from the SA modeto the NSA mode from the wireless power receiving unit 1150 in stepS1605. The mode transition notification message includes a required timeaccording to the mode transition set by the wireless power receivingunit 1150. Therefore, the wireless power transmitting unit 1100 detectsthe required time according to the mode transition included in the modetransition notification message in step S1610. Accordingly, the wirelesspower transmitting unit 1100 may stand by for the preset time andmaintains output power for the required time according to the modetransition in step S1615.

In general, when the wireless power transmitting unit 1100 does notreceive a signal from the wireless power receiving unit 1150 for onesecond, the wireless power transmitting unit 1100 may be set to excludethe wireless power receiving unit 1150 from the wireless power network.However, according to an embodiment of the present invention, when thewireless power transmitting unit 1100 receives the mode transitionnotification message from the wireless power receiving unit 1150, thewireless power transmitting unit 100 may not exclude the wireless powerreceiving unit 1150 from the wireless power network even though thesignal is not received from the wireless power receiving unit 1150 forthe preset required time.

Accordingly, the wireless power transmitting unit 1100 determineswhether the waiting time exceeds the preset required time in step S620.When the waiting time exceeds the preset required time, the wirelesspower transmitting unit 1100 may consider the wireless power receivingunit as a rogue object and excludes the wireless power receiving unitfrom the wireless power network in step S1630. That is, the wirelesspower transmitting unit 1100 terminates the connection with the wirelesspower receiving unit 1150. However, when the waiting time is within thepreset required time, the wireless power transmitting unit 1100communicates with the wireless power receiving unit 1150 again in stepS1630.

According to the above description, when the wireless power receivingunit 1150 switches the SA mode to the NSA mode, the communication withthe wireless power transmitting unit 1100 may be disconnected for apredetermined time. However, even though the signal is not received fromthe wireless power receiving unit 1150 for the preset waiting time, thewireless power transmitting unit 1100 may not exclude the wireless powerreceiving unit 1150 from the wireless power network by receiving theswitching signal from the SA mode to the NSA mode. Accordingly, anunintended error by the mode transition of the wireless power receivingunit can be prevented.

According to the above description, the wireless power transmitting unit1100 may detect a change in a wireless power transmission environmentsuch as the mode transition and may not exclude the wireless powerreceiving unit 1150 from the wireless power network.

Various embodiments of the present invention provide a wireless powerreceiving unit which can notify of, when a wireless power transmissionenvironment change is detected, the change to a wireless powertransmitting unit, and a control method thereof. Further, the presentinvention provides a wireless power transmitting unit which receives asignal for the detection of the wireless power transmission environmentchange from a wireless power receiving unit and a control methodthereof.

In addition, when a charging environment is changed like in a case wherethe wireless power receiving unit switches from the SA mode to the NSAmode, the wireless transmitting unit recognizes a mode transitioncondition of the wireless power receiving unit through a messagenotifying of the change. Accordingly, even though the wireless powertransmitting unit does not receive a signal from the wireless powerreceiving unit for a predetermined time, the wireless power transmittingunit can stand by for a predetermined time until the mode transition iscompleted without a disconnection with the wireless power receivingunit.

While the present invention has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the appended claims. Therefore, various modifiedimplementations can be made without departing from the substance of thepresent invention claimed in the appended claims, and the modifiedimplementations should not be construed separately from the technicalidea or concept of the present invention.

What is claimed is:
 1. A control method of a wireless power receiver,the control method comprising: determining whether to perform a modetransition; transmitting a message indicating the mode transition to awireless power transmitter, the message including a mode transitionperiod; and receiving power for charging from the wireless powertransmitter for a duration of the mode transition period, wherein themessage indicating the mode transition is transmitted for notifying thewireless power transmitter that a communication unit of the wirelesspower receiver will be re-initialized for the duration of the modetransition period.
 2. The control method of claim 1, wherein the modetransition comprises a transition from a stand alone (SA) mode to a nonstand alone (NSA) mode, wherein the wireless power receiver communicateswith the wireless power transmitter based on a communication stackstored in a memory of the communication unit of the wireless powerreceiver, when the wireless power receiver communicates with thewireless power transmitter based on the SA mode, and wherein thewireless power receiver communicates with the wireless power transmitterbased on a communication stack stored outside of the memory of thecommunication unit of the wireless power receiver, when the wirelesspower receiver communicates with the wireless power transmitter based onthe NSA mode.
 3. The control method of claim 2, wherein the determiningwhether to perform a mode transition comprises: communicating with thewireless power transmitter based on the SA mode, when a residualcapacity of a battery of the wireless power receiver is less than aminimum power threshold, determining to perform the mode transition,when the residual capacity of the battery of the wireless power receiveris more than or equal to the minimum power threshold, and communicatingwith the wireless power transmitter based on the NSA mode, afterperforming the mode transition from the SA mode to the NSA mode.
 4. Thecontrol method of claim 1, wherein the mode transition is also fornotifying the wireless power transmitter that no communication betweenthe wireless power transmitter and the wireless power receiver ispossible for the duration of the mode transition period.
 5. The controlmethod of claim 1, wherein the wireless power transmitter maintainstransmitting the power for charging for the duration of the modetransition period starting from a time point at which the message isreceived.
 6. The control method of claim 1, wherein the transmitting amessage comprises: generating a Power Receiving Unit (PRU) dynamicsignal or a PRU alert signal.
 7. The control method of claim 6, whereinthe PRU alert signal includes information regarding the duration of themode transition period.
 8. The control method of claim 7, wherein theinformation regarding the duration of the mode transition periodincludes bits for indicating the duration of the mode transition period,and wherein the bits for indicating the duration of the mode transitionperiod are one of a first value, a second value, a third value and afourth value.
 9. The control method of claim 8, wherein the first valueindicates no mode transition, the second value indicates that theduration of the mode transition period is 2 seconds, the third valueindicates that the duration of the mode transition period is 3 seconds,and the fourth value indicates that the duration of the mode transitionperiod is 6 seconds.
 10. A wireless power receiver, comprising: acontroller configured to determine whether to perform a mode transition;a communication unit configured to transmit, to a wireless powertransmitter, a message indicating the mode transition, the messageincluding a mode transition period; and a power receiving resonatorconfigured to receive power for charging from the wireless powertransmitter for a duration of the mode transition period, wherein themessage indicating the mode transition is transmitted for notifying thewireless power transmitter that the communication unit of the wirelesspower receiver will be re-initialized for the duration of the modetransition period.
 11. The wireless power receiver of claim 10, whereinthe mode transition comprises a transition from a stand alone (SA) modeto a non stand alone (NSA) mode, wherein the communication unitcommunicates with the wireless power transmitter based on acommunication stack stored in a memory of the communication unit of thewireless power receiver, when the communication unit communicates withthe wireless power transmitter based on the SA mode, and wherein thecommunication unit communicates with the wireless power transmitterbased on a communication stack stored outside of the memory of thecommunication unit of the wireless power receiver, when thecommunication unit communicates with the wireless power transmitterbased on the NSA mode.
 12. The wireless power receiver of claim 11,wherein the communication unit is further configured to: communicatewith the wireless power transmitter based on the SA mode, when aresidual capacity of a battery of the wireless power receiver is lessthan a minimum power threshold, determine to perform the modetransition, when the residual capacity of the battery of the wirelesspower receiver is more than or equal to the minimum power threshold, andcommunicate with the wireless power transmitter based on the NSA mode,after performing the mode transition from the SA mode to the NSA mode.13. The wireless power receiver of claim 10, wherein the mode transitionis also for notifying the wireless power transmitter that nocommunication between the wireless power transmitter and the wirelesspower receiver is possible for the duration of the mode transitionperiod.
 14. The wireless power receiver of claim 12, wherein thecommunication unit is a WiFi/Bluetooth Combo integrated circuit (IC).15. The wireless power receiver of claim 10, wherein the wireless powertransmitter maintains transmitting the power for charging for theduration of the mode transition period starting from a time point atwhich the message is received.
 16. The wireless power receiver of claim10, wherein the message comprises a Power Receiving Unit (PRU) dynamicsignal or a PRU alert signal.
 17. The wireless power receiver of claim16, wherein the PRU alert signal includes information regarding theduration of the mode transition period.
 18. The wireless power receiverof claim 17, wherein the information regarding the duration of the modetransition period includes bits for indicating the duration of the modetransition period, and wherein the bits for indicating the duration ofthe mode transition period are one of a first value, a second value, athird value and a fourth value.
 19. The wireless power receiver of claim18, wherein the first value indicates no mode transition, the secondvalue indicates that the duration of the mode transition period is 2seconds, the third value indicates that the duration of the modetransition period is 3 seconds, and the fourth value indicates that theduration of the mode transition period is 6 seconds.
 20. A controlmethod of a wireless power transmitter, the control method comprising:transmitting power for charging to a wireless power receiver; receiving,from the wireless power receiver, a message indicating a mode transitionin the wireless power receiver, the message including a mode transitionperiod; and maintaining transmitting the power for charging for aduration of the mode transition period, wherein the message indicatingthe mode transition is transmitted for notifying the wireless powertransmitter that a communication unit of the wireless power receiverwill be re-initialized for the duration of the mode transition period.21. The control method of claim 20, wherein the mode transitioncomprises a transition from a stand alone (SA) mode to a non stand alone(NSA) mode, wherein the wireless power receiver communicates with thewireless power transmitter based on a communication stack stored in amemory of the communication unit of the wireless power receiver, whenthe wireless power receiver communicates with the wireless powertransmitter based on the SA mode, and wherein the wireless powerreceiver communicates with the wireless power transmitter based on acommunication stack stored outside of the memory of the communicationunit of the wireless power receiver, when the wireless power receivercommunicates with the wireless power transmitter based on the NSA mode.22. The control method of claim 21, wherein the wireless power receivercommunicates with the wireless power transmitter based on the SA mode,when a residual capacity of a battery of the wireless power receiver isless than a minimum power threshold, wherein the wireless power receiverdetermines to perform the mode transition, when the residual capacity ofthe battery of the wireless power receiver is more than or equal to theminimum power threshold, and wherein the wireless power receivercommunicates with the wireless power transmitter based on the NSA mode,after performing the mode transition from the SA mode to the NSA mode.23. The control method of claim 20, wherein the mode transition is alsofor notifying the wireless power transmitter that no communicationbetween the wireless power transmitter and the wireless power receiveris possible for the duration of the mode transition period.
 24. Thecontrol method of claim 20, wherein the maintaining transmitting thepower for charging for a duration of the mode transition periodcomprises: maintaining transmitting the power for charging for theduration of the mode transition period starting from a time point atwhich the message is received.
 25. The control method of claim 20,wherein the message uses a Power Receiving Unit (PRU) dynamic signal ora PRU alert signal.
 26. The control method of claim 25, wherein the PRUalert signal includes information regarding the duration of the modetransition period.
 27. The control method of claim 26, wherein theinformation regarding the duration of the mode transition periodincludes bits for indicating the duration of the mode transition period,and wherein the bits for indicating the duration of the mode transitionperiod are one of a first value, a second value, a third value and afourth value.
 28. The control method of claim 27, wherein the firstvalue indicates no mode transition, the second value indicates that theduration of the mode transition period is 2 seconds, the third valueindicates that the duration of the mode transition period is 3 seconds,and the fourth value indicates that the duration of the mode transitionperiod is 6 seconds.
 29. A wireless power transmitter, comprising: apower transmitting resonator configured to transmit power for chargingto a wireless power receiver; a communication unit configured toreceive, from the wireless power receiver, a message indicating a modetransition in the wireless power receiver, the message including a modetransition period; and a controller configured to maintain transmittingthe power for charging for a duration of the mode transition period,wherein the message indicating the mode transition is transmitted fornotifying the wireless power transmitter that a communication unit ofthe wireless power receiver will be re-initialized for the duration ofthe mode transition period.
 30. The wireless power transmitter of claim29, wherein the mode transition comprises a transition from a standalone (SA) mode to a non stand alone (NSA) mode, wherein the wirelesspower receiver communicates with the wireless power transmitter based ona communication stack stored in a memory of the communication unit ofthe wireless power receiver, when the wireless power receivercommunicates with the wireless power transmitter based on the SA mode,and wherein the wireless power receiver communicates with the wirelesspower transmitter based on a communication stack stored outside of thememory of the communication unit of the wireless power receiver, whenthe wireless power receiver communicates with the wireless powertransmitter based on the NSA mode.
 31. The wireless power transmitter ofclaim 30, wherein the wireless power receiver communicates with thewireless power transmitter based on the SA mode, when a residualcapacity of a battery of the wireless power receiver is less than aminimum power threshold, wherein the wireless power receiver determinesto perform the mode transition, when the residual capacity of thebattery of the wireless power receiver is more than or equal to theminimum power threshold, and wherein the wireless power receivercommunicates with the wireless power transmitter based on the NSA mode,after performing the mode transition from the SA mode to the NSA mode.32. The wireless power transmitter of claim 29, wherein thecommunication unit is a WiFi/Bluetooth Combo integrated circuit (IC).33. The wireless power transmitter of claim 29, wherein the modetransition is for notifying the wireless power transmitter that nocommunication between the wireless power transmitter and the wirelesspower receiver is possible for the duration of the mode transitionperiod.
 34. The wireless power transmitter of claim 29, wherein thecontroller is further configured to control the power transmittingresonator to maintain transmitting the power for charging for theduration of the mode transition period starting from a time point atwhich the message is received.
 35. The wireless power transmitter ofclaim 29, wherein the message comprises a Power Receiving Unit (PRU)dynamic signal or a PRU alert signal.
 36. The wireless power transmitterof claim 35, wherein the PRU alert signal includes information regardingthe duration of the mode transition period.
 37. The wireless powertransmitter of claim 36, wherein information regarding the duration ofthe mode transition period includes bits for indicating the duration ofthe mode transition period, and wherein the bits for indicating theduration of the mode transition period are one of a first value, asecond value, a third value and a fourth value.
 38. The wireless powertransmitter of claim 37, wherein the first value indicates no modetransition, the second value indicates that the duration of the modetransition period is 2 seconds, the third value indicates that theduration of the mode transition period is 3 seconds, and the fourthvalue indicates that the duration of the mode transition period is 6seconds.